The invention resides in an assembly for a holding fixture, and relates more particularly to a "building block" approach of using many similar or identical modular I-beam assemblies comprised minimally of two rows or columns of individual, replaceable linear motion subassemblies to create a larger holding fixture which utilizes an array of translating members.
Holding fixtures are used to retain contoured parts for inspection and/or fabrication purposes and can often be difficult to assemble and maintain without using a modular assembly approach as described by this invention. Many types of linear motion (translating) devices are commercially available and are applicable to the construction method described by this invention. For reference, a lead screw-type approach is shown in the enclosed figures. U.S. Pat. No. 4,684,113 issued to Douglas and Ozer details a universal holding fixture. Such large discrete contour tools are composed of an array of translating members and encounter problems in assembly, wiring, tolerance build-up, repair and servicing.
Additionally, the cost and risk involved with machining large tooling plates and housings from large material stock increases with the number of translating members. In previous holding fixtures, large, costly machine tools must be used to machine these large plates and the versatility to change (expand or contract) the plan form (active area) of the holding fixture is limited by the fixed base and/or intermediate mounting plate size. Higher tool costs result from the larger expenditures and handling costs required to buy dimensionally larger metal stock and subsequently assemble and wire a large, difficult-to-handle fixture. Large holding fixtures need to take advantage of the concept of "modularity". This is because large holding fixtures traditionally have had a pre-set maximum active tool area (maximum usable length and width). Only the individual holding members needed were activated. Nonmodular holding fixtures therefore had to be purchased with inflexible plan forms (overall length and width). Furthermore, troubleshooting, servicing, maintaining, repair and replacement tasks are also difficult to accomplish when fabricating tools in the prior art manner. Additionally, off-line repairs, servicing, and maintenance were slower in prior art designs. By contrast, minimum down-time by rapidly replacing modularized components with acceptable spare modules and/or subassemblies is desired.
The present invention thus takes a "building block" approach and makes use of smaller, low-cost, repetitive elements (e.g. all of the subcomponents of the I-beam assembly), the smaller parts can be manufactured using low-cost, high volume techniques. Assembly, previously a chore due to the difficult access available when building large fixtures, becomes much faster and easier when using an array of modular I-beam assemblies. The use of many similar or identical modular I-beam assemblies within an adjustable frame so that the plan form (active length X width) can be adjusted according to particular needs is new and unobvious. As proposed by the present invention, such use of many similar or identical modular I-beam assemblies which can be rapidly located and installed into an outer frame provides for smaller, pre-tested and pre-assembled units which can be assembled/disassembled, maintained, repaired and stored off-line as needed. Thus, the invention details a modularized approach for building large adjustable holding fixtures.
An object of the invention is to provide an inexpensive means for producing self-adjusting holding fixtures which can be pre-programmed to adjust themselves to three dimensional contours, and can recall or adjust the three dimensional contours from data stored within computer memory.
A further object of the invention is to provide an assembly whereby lower overall assembly and machining costs are major advantages to building large holding fixtures.
Still a further object of the invention is to provide an assembly of the aforementioned type wherein high volume, high production machining techniques can be used with inherently lower machining risk.
A further object of the invention is to provide a plurality of modularized adjustable holding fixture building blocks put together, thereby lowering the overall cost of the assembly by simplifying wiring, assembly, and machining operations.
Yet still a further object of the invention is to provide an assembly with inherently lower overall risk associated with manufacturing thus lowering the overall cost by reducing the magnitude of errors which can cause scrap when using this building block approach to creating larger-scale tooling.
A further object of the invention is to provide an assembly of the aforementioned type which lends itself to easier servicing, faster component replacement, and less down time.
Still yet a further object of the invention is to provide individual I-beam modules which can be designed so that each requires a minimal quantity of electrical connections in particular when using distributed control system logic and utilizing quick-disconnect electrical plugs and locating devices for rapid indexing and installation so that module removal and replacement can be accomplished with minimum down time.
Still a further object of the invention is to provide individual module repair, testing, and/or service which can then take place off-line and to offer a user greater versatility by allowing overall tool size changes inexpensively.
Yet another object of the invention is to provide a device having an overall plan form (length and width) dimensions which can be changed using building block units for larger holding fixtures such that modules can easily be added or subtracted within the limitations imposed by the overall tooling frame.